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European Journal of Applied Sciences – Vol. 11, No. 1
Publication Date: February 25, 2023
DOI:10.14738/aivp.111.14122. Bony, K., Zro, F. G. B., & Guéi, M. A. (2023). Spatial Variability of the Physicochemical Properties of Fallow Soils Formerly Used
for Perennial Crops (Cocoa and Coffee) In the Department of Daloa (Central West of Côte d'Ivoire). European Journal of Applied
Sciences, Vol - 11(1). 533-542.
Services for Science and Education – United Kingdom
Spatial Variability of the Physicochemical Properties of Fallow
Soils Formerly Used for Perennial Crops (Cocoa and Coffee) In
the Department of Daloa (Central West of Côte d'Ivoire)
Kakou Bony
Department of Pedology, Jean Lorougnon Guede University, Daloa, Côte d’Ivoire
Ferdinand Gohi Bi Zro
Department of Pedology, Jean Lorougnon Guede University, Daloa, Côte d’Ivoire
Martinez Arnauth Guéi
Department of Pedology, Jean Lorougnon Guede University, Daloa, Côte d’Ivoire
Abstract
At the present time of recovery of soils formerly used for perennial crops that have
fallen into decline in the Department of Daloa, located in the central-western part
of Côte d'Ivoire, a West African country, there is a need to assess the fertility
potential of these soils in order to avoid a possible rapid failure of the new crops
envisaged. Thus, the present study aims to identify the variables determining the
fertility of these soils, particularly those formerly used for cocoa and coffee
production, and to explain the spatial variability of these properties at the scale of
the study area. To this end, a quantitative characterisation of the physico-chemical
composition of the soils of seven plots that had been abandoned for at least ten
years was carried out. Soil samples were taken from three soil pits dug at each site
in three layers for laboratory analysis. The soil properties resulting from these
analyses were subjected to a variance analysis at the 5% threshold and a
determination of the coefficients of variation. The results obtained made it possible
to highlight the soil parameters that vary to a greater or lesser extent from one site
to another, but which are also crucial for the management of the fertility of the soils
studied.
Key words: Soils, fallows, spatial variability, physico-chemical properties, perennial
crops.
INTRODUCTION
In the Haut-Sassandra region, particularly in the department of Daloa in central-western Côte
d'Ivoire, cocoa and coffee plantations are being abandoned because of the persistent fall in the
price of agricultural products on the world market and the premature ageing of plantations
(Freud et al., 2000; Aguilar et al., 2003; Assiri, 2007), accentuated by a lack of new forest land.
In search of a solution to the decline of their plantations, farmers generally replant with coffee
or cocoa trees or reconvert their soils after felling the first plants that have become
unproductive. In most cases, these attempts are inconclusive because the users of the land are
not aware of its real potential.
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European Journal of Applied Sciences (EJAS) Vol. 11, Issue 1, February-2023
In fact, the soil in general, which supports human activities, is increasingly subject to pressures
and degradation, which means that its important characteristics can be very heterogeneous.
For cultivated soils, for example, the distribution of organic matter is likely to vary greatly over
decametric distances (Arrouays et al., 1997). Such heterogeneity is a factor that limits the good
adaptation of fertiliser doses to the soil characteristics. There is therefore an interest in
increasing and enhancing knowledge of soils, which is lacking in the particular case of coffee
and ca-caja fallow soils in the Department of Daloa, as these soils are in the process of being
reclaimed by their former or new farmers. The present study aims to contribute to the
understanding of this recovery with a view to sustainable agriculture and precision.
MATERIALS AND METHODS
Study Sites
This study was conducted in the department of Daloa, in the Haut-Sassandra Region, in the
centre-west of Côte d'Ivoire. A total of seven sites in seven different localities were selected,
namely the villages of Bla (N6°43'58'' W6°29'37''), Gonaté (N6°53'41'' W6°16'13''),
Loboguguia (N6°47'45" W6°37'18"), Madoguhé (N7°03'77′′ W6°29'18"), Wandaguhé
(N6°50'51" W6°24'55"), Zépréguhé (N6°54'31" W6°22'10") and the town of Daloa (N6°55'03"
W6°22'10") (Figure 1). The sites of Loboguiguia and Zépréguhé are cocoa fallows, while those
of Bla, Daloa, Gonaté, Madoguhé and Wandaguhé are coffee fallows.
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Bony, K., Zro, F. G. B., & Guéi, M. A. (2023). Spatial Variability of the Physicochemical Properties of Fallow Soils Formerly Used for Perennial Crops
(Cocoa and Coffee) In the Department of Daloa (Central West of Côte d'Ivoire). European Journal of Applied Sciences, Vol - 11(1). 533-542.
URL: http://dx.doi.org/10.14738/aivp.111.14043
Figure 1: Location of Daloa department showing the study sites
Data Collection
On each plot, three soil pits were set up. In each pit, three composite soil samples were taken in
the following order: one sample at a depth of 80-120 cm, another at 30-80 cm, and the last at
0-30 cm. Thus, sixty-three soil samples were taken for the entire study, air-dried, sieved to a
mesh size of 2 mm, packaged in labelled plastic bags and sent to the Plant and Soil Analysis
Laboratory located at the Félix Houphouët-Boigny National Polytechnic Institute. The main task
was to carry out the classic soil analyses, i.e. to determine the granulometry, pH, organic carbon,
total nitrogen, organic matter, assimilable phosphorus and exchangeable bases (potassium,
calcium, magnesium and sodium). The cation exchange capacity of the soil, the sum of
exchangeable bases and the base saturation rate were also determined. The methods used to
carry out these different analyses are listed in Table 1. In addition, the sand, silt and clay
contents obtained from the sieve analysis were projected onto the USDA soil textural triangle
to accurately determine the textures of the soils studied.
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Table 1. Summary of applied soil testing methods
Variables Methods of determination
Sand content (S)
Silt content (L) Robinson's Pipette (Douzals, 2000)
Clay content (A)
pH Glass electrode pH meter (Diack et Loum,
2014)
Organic carbon (C) Walkley et Black method (Diack et Loum,
2014)
Total nitrogen (Nt) Kjeldahl modified method (Diack et Loum,
2014)
Assimilable phosphorus (Pass) Olsen modified method (Hilhorst et
Balendonck, 1999)
Calcium content (Ca2+)
Atomic absorption spectrometer (Diack
and Loum, 2014)
Magnesium content (Mg2+)
Potassium level (K+)
Sodium content (Na+)
Cation exchange capacity (CEC)
Sum of exchangeable bases (Sbe) Sbe = Ca2++Mg2++ K++Na+
Base saturation rate (V) V = Sbe/CEC
Analysis of the Data
From the soil analysis results, means, standard deviations and coefficients of variation were
calculated for comparison between soils, when an analysis of variance was performed at the
5% level to assess the spatial variability of the soil properties across the study sites. Whenever
the variables appeared significantly different, the Tukey LSD post-hoc test was applied to
determine the homogeneous groups. All these statistical treatments were carried out using R
software (version 3.6.1).
RESULTS
Physico-Chemical Characteristics of Soils
Tables 2 and 3 present the average values of the variables measured in the soils.
Physically, the soil in Daloa is silty, those in Bla and Madoguhé have a silty-sandy texture, while
in Gonaté, Loboguiguia, Wandaguhé and Zépréguhé, the soils are rather silty-sandy (Tables 2).
At the chemical level, differences also exist between the soils studied (Tables 3). Indeed, given
their pH, the soils of Bla and Wandaguhé (pH = 5.1±0.16), Zépréguhé (pH = 5.0±0.09), Gonaté
and Madoguhé (pH close to 5) are strongly acidic while those of Daloa (pH = 5.9±0.21) and
Loboguiguia (pH = 5.7±0.29) are moderately so. The sums of exchangeable bases measured in
the soils of Madoguhé (Sbe = 1.45±0.18 cmol.kg-1), Loboguiguia (Sbe = 1.44 ±0.18cmol.kg-1) and
Wandaguhé (Sbe = 1.33±0.19 cmol.kg-1) are the lowest, while those of the Daloa soil (Sbe = 3.86
±1.00 cmol. kg-1) is the highest; the values measured in Bla (Sbe = 1.83 ±0.52 cmol.kg-1), Gonaté
(Sbe = 1.82 ±0.38 cmol.kg-1) and Zépréguhé (Sbe = 1.76 ±0.28 cmol.kg-1) are very close to each
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Bony, K., Zro, F. G. B., & Guéi, M. A. (2023). Spatial Variability of the Physicochemical Properties of Fallow Soils Formerly Used for Perennial Crops
(Cocoa and Coffee) In the Department of Daloa (Central West of Côte d'Ivoire). European Journal of Applied Sciences, Vol - 11(1). 533-542.
URL: http://dx.doi.org/10.14738/aivp.111.14043
other and intermediate to those of the first two groups of soils mentioned. With regard to the
saturation of the adsorbent complex, the following decreasing gradient was observed:
53.47±21.49 % in Daloa, 29.29 ±0.19 % in Wandaguhé, 22.14 ±16.29 % and 21.17 ±6.38 % in
Zépréguhé and Madoguhé, 16.64±4.38 % and 15.01±3.08 % in Gonaté and Bla, and finally,
10.84 ±6.77 % in Loboguiguia. For organic matter, the Daloa soil has the highest content (Rate
= 3.18±1.21 %), far ahead of the Bla soil (Rate = 1.97±1.33 %) and those of Gonaté, Loboguiguia,
Madoguhé, Wandaguhé and Zépréguhé where rates vary from 0.99±0.80 to 1.28±0.66 %. This
trend is observed with nitrogen. With assimilable phosphorus, on the other hand, the groups
constituted by the two soils of Daloa and Gonaté are more supplied (43.96±3.0 and 43.80±2.63
g.kg-1), while the other soils (Bla, Loboguiguia, Madoguhé, Wandaguhé and Zépréguhé), with
contents varying from 40.55±2.20 to 42.74±1.29 g.kg-1, are less supplied and similar. With
regard to the cation exchange capacity of the soils (CEC), five groups of soils were distinguished:
the soil of Loboguiguia, which forms the first group, has a very high CEC (CEC = 16.83±8.28
cmol.kg-1); it is followed by the soils of Bla (CEC = 12.38±3.70 cmol.kg-1) and Gonaté (CEC =
11.92±4.74 cmol.kg-1), which have a high CEC; the third group includes the soil of Zépréguhé
(CEC = 11.00±5.37 cmol.kg-1), which has a moderately high CEC; the last two groups are formed
by the soils of Daloa (CEC = 7.95±2.96 cmol. kg-1) and Madoguhé (CEC = 7.33±1.89 cmol.kg-1)
and the Wandaguhé soil (CEC = 4.68±0.87 cmol.kg-1) have normal CEC.
Table 2. Texture of the studied soils
Sites Clay (%) Silt (%) Sand (%) Textures
Bla 20.67 (±0.48) 29.36 (±1.48) 49.70 (±0.48) Sandy clay loam
Daloa 18.52 (±2,51) 36.10 (±1.75) 44.71 (±2.50) Loamy
Gonaté 19.46 (±0.42) 27.35 (±2.42) 52.80 (±5.24) Sandy loam
Loboguiguia 19.84 (±0.73) 19.20 (±0.16) 59.98 (±5.19) Sandy loam
Madoguhé 20.62 (± 0.23) 27.57 (± 1.33) 51.21 (± 2.30) Sandy-clay loam
Wandaguhé 18.97 (±0.07) 20.20 (±0.45) 60.80 (±1.44) Sandy loam
Zépréguhé 19.58 (±0.43) 25.50 (±3.43) 54.70 (±5.19) Sandy loam